The overall goal of this research is to develop an improved system for cryopreservation and storage of human placental/umbilical cord blood (PCB) derived hematopoietic progenitor cells (CD34+), especially as it relates to improving the retention of normal structure and function of frozen/thawed cells and thereby improve clinical outcome (engraftment). With increasing effort directed toward purification and/or in vitro expansion of CD34+ cells for either fundamental research (e.g. research of early events in hematopoiesis) or clinic applications (e.g.,tumor cell purging and T-cell depletion for bone marrow transplantation, development of in utero stem cell transplantation and gene therapy to correct genetic disorders, etc.), there is an associated, increased need for the development of improved preservation methods for these purified and/or in vitro expanded cells to provide "cell banks". In addition, with the increased activity in allograft of purified progenitor cells, the possibility of disease transmission (e.g., HIV and the hepatitis B and C viruses) from use of contaminated donor material requires that only cells from infectious disease-screened donor material be used in such programs. The ability to store frozen progenitor cells would allow sufficient time for adequate screening to be performed. It is the goal of this proposal to develop a closed cryop reservation, storage, and washing system, using novel licensed technology and based on sound biophysical cell-type specific characteristics and mathematical modeling techniques, which will allow efficient and safe use of cryopreserved PCB derived hematopoietic progenitor cells. PROPOSED COMMERCIAL APPLICATIONS: This research will provide a complete cryopreservation system for human PCB that will allow efficient use of cryopreserved material and widespread commercial application in blood bank operations. A particularly important aspect of this system is that it will allow the complete process from freezing, storage, thawing, and transfusion of PCB units in a single closed system, without centrifugal washing.